prized article, for the sake of which the kings often undertook military expeditions, since the elephants were already exterminated on the Euphrates and the Tigris toward the beginning of the tenth century B. C. The ceramics, for which the most excellent raw material was present in all Babylonia, were also remarkable. The clay, which was already washed smooth by the rivers, was ground up so fine that clay writing tablets, for instance, were made of such superlative quality that they could be covered with writing so small as hardly to be read without a microscope.

The Babylonians are our predecessors in the art of printing. We have matrices in clay and in wood. The writing to be multiplied was first carved in wood, then cast in clay, and could then be imprinted upon any number of clay tablets.

A highly developed branch of industry was the art of weaving and embroidery, although we have no specimen of the material. We can form an idea of this art from the representations of the Egyptians and the Babylonians. The Babylonians understood how to weave very thin fabrics as well as the thickest. I myself have seen a clay tablet in London which had been laid upon a piece of linen, so that even now the position of the threads and the excellence of the fabric to which they belonged can be estimated.

The tanner's trade, moreover, was highly developed. This, too, can be judged of only through pictorial representations. According to these, shoes and the harness and saddles of horses were elaborately worked.

Those who carried on industry were partly free, partly slaves; the former received wages, the latter were hired or rented. The owners of the slaves received from the latter, if they were skilled laborers, a fixed income. This must be clearly recognized in the picture of the social relations in Babylon. It is a matter of course, that here the interests of the owners and those of the laborers must have been diverse, and that, in spite of the immense population of Babylon, its political conditions must have been very unstable, because only the rich-that is, the dwindling minority-had an interest in the maintenance of order. Babylon had never been able to attain the position of Rome, where the Plebs constantly obtained more rights.

As for the instruments of labor in Old Babylon, they were not highly developed. On the other hand, a high degree of technical perfection was wrought out with these poor instruments. Among us the

reverse is the case. The tools are very good, but the skill of the human hand has greatly diminished. Whether a division of labor in the modern sense existed in Babylon cannot be yet made clear. There are, nevertheless, a number of facts which would point to it.

According to the representations in the reliefs, the citizens attended public gatherings on state occasions and temple ceremonies, richly adorned and with the insignia which distinguished them as citizens; that is, in flowing garments, with large and artistically made head-dresses, with a seal ring upon the finger, with staff in hand, with girdle and beautifully embroidered leather shoes. In everyday work, on the contrary, we see the same citizens carrying on their business in shirt and apron. Unfortunately, the remains which are at hand come mostly from temples and palaces, and therefore we can form a clear picture only of great state functions.

Several scholars maintain that in Babylon only the temples and palaces are to be considered as great buildings, while the inhabitants lived in primitive huts. This is an untenable view. Portions of foundation walls which belonged to private houses have been discovered, and we are justified in the assumption that Babylon, so long as it existed, made, with its houses, the impression of a great city. One must not forget, withal, that it was an oriental city which required another kind of architecture than that of our great cities. Upon the main streets, which were paved with stone, little outbuildings, such as we still see in oriental cities, which must have served as booths or bazaars, were erected before the houses. There, as in the gates of the temples and palaces, handiwork and traffic were briskly carried on.

Money, the medium of exchange, received its first and best improvement there. It had passed from the conception of barter to the refined conception of value. In even earlier times gold and silver money, and also as subsidiary coinage, copper, bronze, and iron were used. The further the development went the more need there must have been of having the metals in a fixed form and in certain proportions of weight in order that there might be no necessity for weighing the metals each time. It was therefore molded into bars and rings. Unfortunately, no such coins have been preserved, but we have written references to them. The unit of value was the mine. This contained 60 sheqels, and the latter had again subdivisions, but these varied. From the two first developments of money arises the third; the use of money as capital; that is, interest-bearing capital. We have, in about 2300 B. C., the

transition, as people pledged themselves to work a certain length of time for a sum of money which they must return later.

Exchange was known in Babylon, and there are statements of the changes in value of money. Moreover, the ratio of value between gold and silver was fixed.

This fine development of the relations of value was accompanied by another the relation of the purchasing power of money to livelihood. A number of documents exist which show that the living expenses of the laborers cannot have been very high, and this agrees with what we know of the Orient from other sources. The soil furnishes the necessaries of life without man's having to take much trouble. Consequently, idleness and beggary are nowhere more widespread than in the Orient. Nowhere is industry urged forward in a more brutal way. There are many reliefs from Babylon and Egypt which show laborers constantly driven by blows from a stick; during the transportation of colossal weights an overseer with a club stands behind every three or four laborers.

CONCLUSION

During the correction of the preceding sketch, which the editor of the Mittheilungen has sent to the press half against my will, but which I will not now withdraw, since otherwise I should be obliged to let it lie for many years to come without finding the time to work it over thoroughly, two gaps came to my special notice, the filling up of which, however, is subsequently to take place elsewhere. The professional position of the priests will probably be described by Zimmern in his contributions to the knowledge of the Babylonian religion; that of the judges will be treated by Kohler in the fourth part of the work published by Kohler and myself upon Babylonian juridical life.

Translated from Mitteilungen der Vorderasiatischen Gesellschaft, Berlin, 1896.

PHYSICS

THE MOST IMPORTANT ADVANCES in theoretical Physics during the last thirty years have been connected with the consideration of waves in the ether. In 1873 and even before, J. Clerk Maxwell developed his theory that electricity like light is a wave in the ether. The main proof of this theory rested upon the fact that it could be made to account for electrical phenomena and that the speed of light and electricity seemed to be approximately the same. In 1888 Hertz of Germany succeeded in actually detecting waves in electricity by the method described below. The gradually acquired knowledge of their production and control have resulted in the wireless telegraph, the details of which are given under this head.

The discovery of Crookes' rays and of the X-rays by Röntgen points the way to a knowledge of new forms of radiation.

JAMES CLERK MAXWELL

JAMES CLERK MAXWELL was born in 1831. He attended Edinburgh from 1847 to 1850, then entered Cambridge and was graduated in 1854, taking the honor of second wrangler.

From 1856 to 1860 he taught in Marichal College, Aberdeen, and from 1860 to 1868 in King's College, London.

He was a mathematician at fifteen, and several of his papers were read before the Royal Society of Edinburgh before he was nineteen. In 1867 he took up the question of electricity and strove to find a theory of it which would not include such a conception as action from a distance. This developed into the theory that electricity is a condition of stress or strain in the ether, in other words, that it is a wave in the same medium as light and travels at the same rate of speed. Hertz's experiments in 1888 have done much to confirm this theory, and such inventions as wireless telegraphy are a direct result.

Maxwell died in 1879.

ELECTRICITY A WAVE IN THE ETHER

In several parts of this treatise an attempt has been made to explain electromagnetic phenomena by means of mechanical action transmitted from one body to another by means of a medium occupying the space between them. The undulatory theory of light also assumes the existence of a medium. We have now to show that the properties of the electromagnetic medium are identical with those of the luminiferous medium.

To fill all space with a new medium whenever any new phenomenon is to be explained is by no means philosophical, but if the study of two different branches of science has independently suggested the idea of a medium, and if the properties which must be attributed to the medium in order to account for electromagnetic phenomena are of the same kind as those which we attribute to the luminiferous medium in order to account for the phenomena of light, the evidence for the physical existence of the medium will be considerably strengthened.

But the properties of bodies are capable of quantitative measurement. We therefore obtain the numerical value of some property of the medium, such as the velocity with which a disturbance is propagated through it, which can be calculated from electromagnetic experiments, and also observed directly in the case of light. If it should be found that the velocity of propagation of electromagnetic disturbances is the same as the velocity of light, and this not only in air, but in other transparent media, we shall have strong reasons for believing that light is an electromagnetic phenomenon, and the combination of the optical with the electrical evidence will produce a conviction of the reality of the